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Tag archive: phosphorus

WATCH: Is it time to re-think P critical levels in WA?

Applying phosphorus (P) to soils with seemingly adequate P stocks can boost yield. Trials in WA are showing crop response to P above critical levels. Critical levels indicate if a crop will respond to more of a certain nutrient. Above the critical level, there’s less than a 10% chance of […]

Sow close to the row to boost crops after a dry year

On-row or edge row sowing means sowing a new crop immediately alongside or in the previous crop row. Grain crops are usually sown inter-row (between the old crop rows). On-row sowing for phosphorus On-row sowing can make use of last year’s phosphorus (P) fertiliser. Phosphorus is not a very mobile […]

What is the benefit of deeper phosphorus sampling?

Testing deep phosphorus (P) can improve fertiliser recommendations with a more accurate look at soil P stocks. It can help to know how much P is in the profile, and where it is. The topsoil is usually the most nutrient dense part of the soil. Maturing crops also rely on […]

What is the phosphorus buffering index?

The Phosphorus Buffering Index (PBI) approximates a soil’s ability to ‘fix’ phosphorus (P). Soils with a high PBI quickly and tightly bind fertiliser P making it unavailable to plants. Low PBI soils can’t lock-up much P, leaving most applied P for plant uptake. Use PBI to improve interpretation of critical […]

How to adjust phosphorus after a dry year

A poor or failed crop last season will affect nutrient budgets this season. Cereal hay removes about 1–2 kg of phosphorus (P) per tonne of dry matter. Canola removes about 3 kg of P per tonne (see Table 1). Table 1. Comparison of nutrients removed in grain, straw, canola hay, […]

What is the DGT Phosphorus test and when should you use it?

The Diffusive Gradient in Thin-films (DGT) Phosphorus is an alternative P soil test. Colwell-P can overestimate available P on calcareous soils, and acid gravel soils. How does the DGT test work? The DGT is a cylindrical plastic device that uses an iron oxide gel as a P-sink, which attracts available […]

Tillage increases P accessibility

Tillage can redistribute phosphorus (P) within the top 10 cm of the soil. P often becomes concentrated at the soil surface, especially in no-till paddocks. Getting P deeper into the soil is important in dry seasons when the active root zones are deeper. Trials tested the response of wheat to […]

Our top picks from the fertiliser industry conference

New science topped the agenda at the 2017 Australian Fertilizer Industry Conference. Fertilizer Australia hosted the conference in Torquay, Victoria. Of the many presentations, the following two papers are relevant to Australian growers and crop nutritionists. Phosphorus and soil biology Dr Cassandra Schefe works with Monash University. Her research investigates microbe […]

Is Phosphorus building up in your paddock?

a mountain of soil phosphorus with a stickman scratching his head.

Phosphorus may be over applied in Southern Australian grain farms. A recent survey by IPNI found 80% of paddocks had more P applied than removed over a 3–5 year period. Nutrient Performance Indicators (NPIs) revealed that on average, 0.69 kg P is removed per kg P applied. Some farms may […]

Starter and residual P give strong early vigour in the north

Aerial photograph of starter and deep P trial site plots

This season, starter phosphorus (P) is producing strong early crop vigour. Deep P placement effects and the response to starter P are being documented at a long term monitoring site at Terry Hie Hie, in far north New South Wales.   The trial site compares plots with different rates of […]

New deep P tool calculates the benefits and payback for you

Subsoil phosphorus (P) deficiency costs growers in Queensland and Northern NSW around $80–100 million each year in reduced yield. Deep P fertiliser applications into the subsoil can improve yield but are a long-term decision. They are moderately expensive and returns are not immediate. The Deep-P calculator helps Northern region growers […]

Do late sown crops need extra Phosphorus?

As winter sowing dates get later a crop’s potential response to Phosphorus (P) fertiliser rises, at the same time absolute yield potential is falling. This raises the question of what adjustments might need to be made to P fertiliser rates. Plant physiology indicates that later sown crops should be more […]